1. Field of the Invention
The present invention relates to thermal circuit protector devices which also function as ON/OFF switches, and deals more particularly with a structure that is simpler and less expensive to manufacture. The thermal circuit protector/switch structure also prevents a continuance or a cycling of an overload condition in the event manual override is attempted.
2. Description of the Prior Art
Switches for use either as a thermal protector circuit breaker or switch are known. Snap action bi-metallic elements have been embodied in similar thermal protectors which employ a flag of insulating material to project between the switch contacts when the bi-metal element senses an overload condition. See U.S. Pat. Nos. 5,089,799 and 5,264,817 for examples of thermal protective switches of the type utilizing such a flag.
Other thermal protective devices that serve a switch function operate via a push button action, and require that the push button be manually pulled out after the device trips the circuit in order to reset the circuit protector. Butler, U.S. Pat. No. 3,311,725 illustrates a circuit breaker/switch of this general type.
Still other thermostatic switches have a snap action disc that can be reset by a push button. See U.S. Pat. Nos. 4,791,397 and 4,628,295 for examples of disc type devices.
Although much more complicated and therefore more expensive to manufacture, thermal circuit breakers are also known. See U.S. Pat. Nos. 4,931,762; 4,937,548; and 4,258,349 for examples.
Another version of a thermal circuit breaker and switch, by the same inventor herein, uses the bi-metal element as the contact arm. See U.S. Pat. No. 5,847,638.
Still another approach to providing a rocker switch style thermal circuit breaker is shown in U.S. Pat. No. 5,491,460. However, this patent, like others of its type, requires many metal components, and metal spring elements to achieve the `trip free` operation necessary in such protective breakers. See also U.S. Pat. Nos. 5,889,457 and 5,451,729 wherein many specially formed metal components and springs are required to provide a trip free rocker switch style thermal breaker.
The general purpose of the present invention is to provide a thermal circuit breaker and switch that does not require a flag, and has both the appearance and functional capability of a conventional rocker switch, and wherein the device is also capable of "trip free" operation so that even if manually held in the `on` or closed position, will not result in re-closing of the contacts and hence reheating of the bi-metal. The present invention avoids the stresses imposed on the bi-metal element when used as a contact arm although the bi-metal is provided in the circuit path. Individual contact and trip actuators are provided to avoid stressing the bi-metal, thus improving both accuracy and stability of operation. While slightly more complicated and expensive than the embodiment using the bi-metal as the contact arm, this invention remains less expensive to manufacture than other thermal circuit breaker designs which have the bi-metal separate from the contact.